MEMBRANE FLUIDITY OF ESCHERICHIA-COLI DURING HEAT-SHOCK

The excimer-forming fluorophore dipyrenylpropane has been used to meas ure the relative fluidity of total membranes isolated from Escherichia coil grown at 30 or 45 degrees C, or exposed to a heat-shock from 30 to 45 degrees C for various periods of time. Parallel experiments were performed using [S-35]methionine pulse-labeling of cells, to study th e induction of heat-shock proteins (HSPs) at different times after the sudden change in E. coli growth-temperature from 30 to 45 degrees C. Results suggest that upon an abrupt temperature upshift from 30 to 35 degrees C, membrane fluidity adjustment to the steady-state level at t he high temperature, takes place during the E. coli heat-shock respons e.